Plastic lenses have a high refractive index and a high Abbe number and are light-weight, difficult to crack, and can be dyed as compared with inorganic lenses. Accordingly, they have been rapidly spreading as optical materials for eyeglass lenses, camera lenses, or the like on a commercial scale. Various molded products for lenses have hitherto been developed and used. A typical example of these materials may be an optical molded product obtained from a polymerizable composition including an isocyanate compound and a thiol compound (Patent Document 1).
Moreover, for recent eyeglass lenses, there are many cases where processing for increasing added value is carried out by, for example, providing a silicon-based hard coat layer on a lens of a substrate in order to improve hardness; and providing an inorganic oxide-based antireflection coat layer in order to suppress surface reflection. On the other hand, impact resistance may be lowered by providing these coat layers in some cases.
With a recent spread of sports glasses and children's glasses, there is a demand for eyeglass lenses having high impact resistance, such as ones that do not crack even under an impact when eyeglasses are dropped during heavy exercise or when an object such as a ball collides with a lens.
As materials for eyeglass lenses, which have high impact resistance, polycarbonate or polyureaurethane materials have been proposed.
For example, Patent Document 2 discloses that a polyureaurethane lens including a hard coat layer or an antireflection coat layer does not crack even when a missile of 1.06 grams collides therewith at a speed of 150 feet in accordance with the ANSI 287.1 standard, and thus, has very high impact resistance. However, for the manufacture of the polyureaurethane lens, it is required to prepare a prepolymer obtained by reacting an isocyanate component with an alcohol component at a high temperature 100° C. or more in advance, and a specially designed molding machine is also required during molding. Accordingly, the method for manufacturing the lens is very complicated.
On the other hand, from the viewpoints that polythiourethane materials do not require a prepolymerization reaction, and further, a special molding machine is not required, it is possible to more conveniently manufacture a lens, as compared with polyureaurethane materials. Thiourethane-based lenses including a hard coat layer and an antireflection coat layer, which have improved impact resistance, have hitherto been proposed (Patent Documents 3 to 7). These documents disclose a polymerizable composition including a specific alicyclic isocyanate compound, an aliphatic isocyanate compound, and a polythiol compound, as a composition for obtaining a lens substrate.
In addition, in the case of providing a coat layer on the surface of a lens, the surface of the lens is subjected to a surface treatment with an alkaline liquid in advance in some cases. Due to this alkali treatment, the surface of the lens has white turbidity or the like in some cases.
It is an object of the present invention to provide a polymerizable composition which has high impact resistance as well as excellent alkali resistance and appearance, as compared with a polythiourethane-based lens including a hard coat layer and an antireflection coat layer in the related art, and is capable of obtaining a lens having excellent impact resistance even in the case where a primer layer is not disposed between a base layer and a hard coat layer or antireflection coat layer.